Absolutely! Besides HIV infection which should be excluded in all patients with recurrent bouts of bacterial pneumonia irrespective of age, “selective polysaccharide antibody deficiency”, also known as “specific antibody deficiency” or SAD, should also be excluded (1-3). SAD in adults with recurrent pneumonia is not rare, having been reported in about ~8% of such patients (4).
Think of SAD when your adult patient presents with recurrent bouts of bacterial pneumonia despite having normal serum total immunoglobulin (IgG, IgA, and IgM) levels and IgG subtypes (1-3). These patients have a normal response to tetanus toxoid (a protein) but cannot mount adequate antibody response against polysaccharide antigens of pathogens such as pneumococcus.
One way to diagnose SAD in a suspected patient is through vaccination with 23-valent pneumococcal polysaccharide vaccine (PPSV23). In patients with low baseline antibody titers to many of the capsular types of pneumococcus included in the PPSV23, a suboptimal response (defined by the lab) 4 weeks after vaccination with PPSV23 is suggestive of SAD. Remember that if your patient has already been vaccinated with the 13 valent pneumococcal conjugate vaccine (PCV13), you can only evaluate for the response to serotypes included in the PPSV23 only.
Although there are no randomized-controlled studies and treatment should be individualized, immunoglobulin replacement may reduce the risk of future bouts of pneumonia in SAD (2-3).
Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!
Subscribe to Blog via Email
1. Cohn JA, Skorpinski E, Cohn JR. Prevention of pneumococcal infection in a patient with normal immunoglobulin levels but impaired polysaccharide antibody production. Ann Allergy Asthma Immunol 2006;97:603-5. https://www.ncbi.nlm.nih.gov/pubmed/17165266
2. Cheng YK, Kecker PA, O’Byrne MM, Weiler CR. Clinical and laboratory characteristics of 75 patients with specific polysaccharide antibody deficiency syndrome. Ann Alergy Asthma Immunol 2006;97:306-311. https://www.ncbi.nlm.nih.gov/pubmed/17042135
3. Perez E, Bonilla FA, Orange JS, et al. Specific antibody deficiency: controversies in diagnosis and management. Front Immunol 207;8:586. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5439175/pdf/fimmu-08-00586.pdf
4. Ekdahl K, Braconier JH, Svanborg C. Immunoglobulin deficiencies and impaired immune response to polysaccharide antigens in adult patients with recurrent community acquired pneumonia. Scand J Infect Dis 1997;29:401-7. https://www.ncbi.nlm.nih.gov/pubmed/9360257